This invention relates to radiation curable coating compositions which when cured form highly abrasion resistant coatings for most any substrate.
In the past, many curable or crosslinkable compositions have been developed in the art for use as coatings for clear plastics and the like which when cured offer varying degrees of abrasion and solvent resistance. Among such compositions are fluorocarbon-vinyl ether copolymers crosslinked with polysilicic acid, melamine-formaldehyde coatings, polyurethanes, polysiloxanes, polyakyls, polyallyldicarbonates, and polyfunctional acrylics. Such coatings have been applied to a wide variety of polymeric substrates including acrylic sheeting, polycarbonates, polyesters and the like. These compositions are generally applied to the substrate by any known method such as dipping, brushing or spraying and are cured at either high temperature or at low temperature in the presence of a catalyst. Ultraviolet curable coatings based on unsaturated polyester resins, including polyacrylics, and containing a photoinitiator have also been described in the art.
The present invention deals with dipentaerythritol polyacrylate-based compositions which can be applied as thin coatings to a variety of substrates and cured by actinic radiation in the absence of a photoinitiator or photocatalyst. Precured coatings of these compositions are dust-free, level out well on the substrates and are stable against air inhibition of cure such that they can be cured in air hours after application to the substrate. On curing, coatings are formed exhibiting high abrasion resistance and stress crack resistance. Such coatings are additionally scratch resistant and are not attacked by chemical or organic solvents.